1. Field of the Invention
This invention relates to the processing of a nonpetroleum organic liquid such as fats, animal and vegetable oils; and more particularly to the quality improvement (solids, soaps. etc.) of such an organic liquid by a multistep treating process.
2. Description of the Prior Art
Many nonpetroleum organic liquids (e.g., fats, vegetable and animal oils) are used for human consumption and other utilizations. The organic liquid can be purified chemically and mechanically to remove solids and to improve chemical properties, color, odor and enchance storage stability, to make it more suitable for ultimate utilization. Present day treatment of crude fat, animal and vegetable oils, as organic liquids, consist generally of the steps of refining, bleaching, and deodorization, as well as hydrogenation and winterizing. The term "refining" refers to any purification treatment designed to remove undesired materials such as free fatty acids, phosphatides, or mucilaginous material, or other gross impurities in the organic liquid. The term "bleaching" is reserved for treatment designed solely to reduce the color of organic liquid. The term "deodorizing" is used for the treatment which has as its primary object to remove the traces of constituents which give rise to flavors and odors from the organic liquid.
The refining of an organic liquid usually employs aqueous reagents in the nature of alkali or acid to remove certain impurities, such as free fatty acids and certain color bodies. Also, the refining treatment can improve the color and odor characteristics of the organic liquid. For example, vegetable oils, especially those subjected to oxidization, suffer from increased color components especially the red and yellow tints. A prebleach step can be used to effect the removal of various color bodies, residual moisture and impurities such as residual soaps formed by the alkali reagent reactions. A solid adsorbent, such as bleaching clay, is admixed as a fine dispersion into the refined organic liquid, the mixture heated, dehydrated and deareated in vacuum dryers or in atmospheric tanks, and then filtered in mechanical equipment such as leaf filters. The filtered organic liquid which is an acceptable product in the industry (good color and low solids), is usually subjected to hydrogenation to provide a consumer product (e.g., shortening) or used directly for various other utilizations. For decades, the filtered organic liquid has been accepted as of proper high purity for the hydrogenation procedure.
In hydrogenation treatment, the organic liquid is admixed with a small amount of a hydrogenation catalyst in a finely dispersed state. Then, the mixture is subjected to superatmospheric hydrogen gas at elevated temperatures for a selected period of time until the desired reaction of the unsaturated and hydrogen reducible materials is reached in the organic liquid. After hydrogenation is completed, the organic liquid and the dispersed hydrogenation catalyst are separated (e.g., using precoated leaf filters). The effectiveness of the hydrogenation treatment is determined by several factors such as quality of the product in lovibond color, solids content, metals, water content, acid numbers, and so forth. The time required to reach a certain level of hydrogenation, the degree of hydrogenation in total consumption and saturation of desired unsaturate bonds in the organic liquid have a substantial weight in the economics of the hydrogenation treatment.
The industry has assumed for decades that if the organic liquid is given a proper (optimum) prebleaching treatment, the conditions of hydrogenation treatment solely determine the quality of the product organic liquid. Stated in another manner, in the proper prebleaching treatment, the purified organic liquid is filtered mechanically to optimum color and impurities quality. Then, only the hydrogenation conditions control the quality of the hydrogenated organic liquid.
In arriving at the present invention, the filtered organic liquid from mechanical filters was subjected to a unique purification step and then hydrogenated. The effectiveness of the hydrogenation treatment was increased and the quality of the hydrogenated organic liquid was also improved. Under these circumstances, the unique purification step was substituted directly for the mechanical filtration using leaf filters. Again, the unexpected increase in hydrogenation treatment effectiveness and improved product quality of the hydrogenated organic liquid were obtained. An experimental program provided data to confirm these unique results attributed to this unique purification step.
The present invention is a process which employs the unique purification step in a combination of steps familiar in everyday practices in the refining, prebleaching and hydrogenation of organic liquids. However, the resultant combination of steps produces greatly improved results not obtained with conventional prebleaching treatments using mechanical filtration of the organic liquid. Furthermore, the unique purification step provides substantially complete removal of all finely divided solid materials, moisture and alkali soaps that can be considered deleterious impurities effecting hydrogenation efficiency and product quality of the hydrogenated organic liquid. It is believed that the complete removal of these impurities promotes an increased susceptibility of the organic liquid to hydrogenation.